Reinaldo de Carvalho wrote:
"Don't need" but "could be". The standards *could be suggest* something about loop detection.
only if you can get consensus, which is much harder than you might think. while almost everybody now agrees that putting the envelope recipient in a header (except for mail delivered to a single recipient) was a borked idea, there is no consensus about loop detection. (or if you prefer, "Apparently-To" is ok, but given that it has already been used the wrong way, it is easier to "obsolete" it rather than to give 100 lines explaining how/when/why to [not] use it).
add to this that getting consensus on smtp related drafts/rfcs is a lot harder than "it should". not only because the spam and malware problem makes some people think in "transient solutions" terms, but also because smtp has been implemented since long, and a lot of people have different ideas of what is best to do. as a result, I don't expect changes (other than clarifications or esmtp extensions) in the smtp specs in the short future.
